Microelectronic die packages with metal leads, including metal leads for stacked die packages, and associated systems and methods

ABSTRACT

Microelectronic die packages, stacked systems of die packages, and methods of manufacturing them are disclosed herein. In one embodiment, a system of stacked packages includes a first die package having a bottom side, a first dielectric casing, and first metal leads; a second die package having a top side attached to the bottom side of the first package, a dielectric casing with a lateral side, and second metal leads aligned with and projecting towards the first metal leads and including an exterior surface and an interior surface region that generally faces the lateral side; and metal solder connectors coupling individual first leads to individual second leads. In a further embodiment, the individual second leads have an “L” shape and physically contact corresponding individual first leads. In another embodiment, the individual second leads have a “C” shape and include a tiered portion that projects towards the lateral side of the second casing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 14/029,455filed Sep. 17, 2013, now U.S. Pat. No. 8,906,744, which is divisional ofU.S. application Ser. No. 13/492,554 filed Jun. 8, 2012, now U.S. Pat.No. 8,536,702, which is a divisional of U.S. application Ser. No.12/955,666 filed Nov. 29, 2010, now U.S. Pat. No. 8,198,720, which is acontinuation of U.S. application Ser. No. 11/863,425 filed Sep. 28,2007, now U.S. Pat. No. 7,843,050, which claims foreign prioritybenefits of Singapore Application No. 200705422-4 filed Jul. 24, 2007,now Singapore Patent No. 149726, each of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure is directed generally to microelectronic diepackages with metal leads, and more particularly to metal leadsconfigured for stacked die packages.

BACKGROUND

Packaged microelectronic assemblies, such as memory chips andmicroprocessor chips, typically include a microelectronic die mounted toa substrate and encased in a plastic protective covering. The dieincludes functional features, such as memory cells, processor circuits,and interconnecting circuitry. The die also typically includes bond padselectrically coupled to the functional features. The bond pads areelectrically connected to pins or other types of terminals that extendoutside the protective covering for connecting the die to busses,circuits, or other microelectronic assemblies.

In one conventional arrangement, the die is mounted to a supportingsubstrate (e.g., a printed circuit board), and the die bond pads areelectrically coupled to corresponding bond pads of the substrate withwirebonds. After encapsulation, the substrate can be electricallyconnected to external devices with solder balls or other suitableconnections. Accordingly, the substrate supports the die and provides anelectrical link between the die and the external devices.

In other conventional arrangements, the die can be mounted to a leadframe that has conductive lead fingers connected to a removable frame.The frame temporarily supports the lead fingers in position relative tothe die during manufacture. Each lead finger is coupled to acorresponding bond pad of a die (e.g., via a wire bond or a metalredistribution layer), and the assembly is encapsulated in such a waythat the frame and a portion of each of the lead fingers extend outsidethe encapsulating material. The frame is then trimmed off, and theexposed portions of each lead finger connect the die to externalcomponents. In general, individual lead fingers can be bent and thencoupled to a corresponding external bond pad.

Die manufacturers have come under increasing pressure to reduce thevolume occupied by the dies and yet increase the capacity of theresulting encapsulated assemblies. To meet these demands, diemanufacturers often stack multiple dies on top of each other to increasethe capacity or performance of the device within the limited surfacearea on the circuit board or other element to which the dies aremounted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of a stacked system that includesmicroelectronic die packages configured and stacked in accordance withan embodiment of the disclosure.

FIG. 2A is a top view of a microelectronic assembly that includes aframe, a release layer, and a support substrate.

FIGS. 2B and 2C are partially exploded cross-sectional side views of theassembly of FIG. 2A.

FIG. 3A is a top view of the assembly of FIG. 2A having microelectronicdies positioned within openings of the frame.

FIGS. 3B and 3C are cross-sectional side views of the assembly of FIG.3A.

FIG. 4A is a top view of the assembly of FIG. 3A encapsulated in adielectric material.

FIGS. 4B and 4C are cross-sectional side views of the assembly of FIG.4A.

FIGS. 5A and 5B are cross-sectional side and bottom views of theassembly of FIG. 4A after removing the support substrate.

FIG. 6 is a cross-sectional side view of the assembly of FIGS. 5A and 5Bafter forming a spacer layer.

FIG. 7 is a cross-sectional side view of the assembly of FIG. 6A afterpartial removal of the dielectric material.

FIG. 8A is a cross-sectional side view of the assembly of FIG. 7 aftersingulation and formation of metal leads.

FIG. 8B is a cross-sectional side view of the assembly of FIG. 7 aftersingulation and formation of metal leads in accordance with analternative embodiment of the disclosure.

FIG. 9 is a cross-sectional side view of a stacked system that includesmicroelectronic die packages configured and stacked in accordance withan alternative embodiment of the disclosure.

FIG. 10 is a cross-sectional side view of a stacked system havingmicroelectronic die packages that include dies of different sizes inaccordance with an embodiment of the disclosure.

FIG. 11 is a cross-sectional side view of a stacked system having metaltraces for selectively electrically coupling individual microelectronicdie packages in accordance with an embodiment of the disclosure.

FIG. 12 is a schematic illustration of a system in which themicroelectronic die packages and stacked systems may be incorporated.

DETAILED DESCRIPTION

Specific details of several embodiments of the disclosure are describedbelow with reference to semiconductor devices and methods forfabricating semiconductor devices. The semiconductor components aremanufactured on semiconductor wafers that can include substrates uponwhich or in which microelectronic devices, micromechanical devices, datastorage elements, optics, read/write components, and other features arefabricated. For example, SRAM, DRAM (e.g., DDR/SDRAM), flash memory(e.g., NAND flash memory), processors, imagers, and other types ofdevices can be constructed on semiconductor wafers. Although many of theembodiments are described below with respect to semiconductor devicesthat have integrated circuits, other types of devices manufactured onother types of substrates may be within the scope of the invention.Moreover, several other embodiments of the invention can have differentconfigurations, components, or procedures than those described in thissection. A person of ordinary skill in the art, therefore, willaccordingly understand that the invention may have other embodimentswith additional elements, or the invention may have other embodimentswithout several of the features shown and described below with referenceto FIGS. 1-12.

FIG. 1 is a cross-sectional side view of one embodiment of a stackedsystem 100 having a plurality of die packages 10 (identifiedindividually by reference numbers 10 a-d). Individual die packages 10can include a microelectronic die 12, a molded dielectric casing 14, andmetal leads 16 (or metal contacts) that are laterally spaced apart fromthe casing 14. The casing 14 has lateral casing sides 21, a top casingside 22, and a bottom casing side 23, and the casing 14 encapsulates atleast a portion of the die 12 and the leads 16. In the example shown inFIG. 1, individual leads 16 are coupled to the bottom casing side 23 andproject, at least in part, towards an above-located die package or thetop of the stacked system 100. Individual leads 16 can further includean exterior lead surface 25 and an interior lead surface 26 having aregion 27 that generally faces an individual lateral casing side 21. Theinterior surface region 27 of the illustrated example is located on anangled lead portion 28 of an individual lead 16, which is spacedlaterally apart from the lateral casing side 21 by a lateral leadportion 29 of the lead. The die packages 10 can further include metaltraces 32 that electrically couple the leads 16 to the die 12 and adielectric spacer layer 34 encasing the traces 32 and a portion of anactive side of the die 12. The die packages 10 can also include packagebond pads 36 coupled to the traces 32. The stacked system 100, forexample, has an interposer substrate 102 with metal bump pads 104electrically connected to the package bond pads 36 at the first diepackage 10 a by bond pad connections 106.

The embodiment of the stacked system 100 shown in FIG. 1 includes thefour stacked die packages 10 a-d physically coupled together atcorresponding top and bottom sides by adhesive layers 112 a-c, and theleads 16 of the die packages 10 a-d are electrically coupled together byexternal inter-package connectors 114. The connectors 114, for example,can be metal solder lines formed along portions of the exterior leadsurfaces 25 corresponding to sets of vertically aligned leads 16 andoptionally along portions of the interior lead surfaces 26. Thus, themetal pads 104 are electrically coupled to microelectronic dies withinthe die packages 10 a-d through conduction paths that include the leads16 and the connectors 114. In many embodiments, and as shown in FIG. 1,the leads 16 corresponding to the die packages 10 a-c extend beyond thetop casing side 22, contact a portion of the exterior lead surface 25 onan above-located die package 10, and are held to the portion of theexterior lead surface 25 by an individual connector 114. Additionally,the embodiment of the individual connectors 114 shown in FIG. 1 attachto portions of the exterior and interior lead surfaces 25-26 along theangled and lateral lead portions 28-29. In alternative embodiments, theconnectors 114 may attach only to a portion of the exterior lead surface25 along the angled lead portion 28 and, optionally, a portion of theexterior lead surface 25 along the lateral lead portion 29. Accordingly,several embodiments of the connectors 114 project at least laterallyoutward from the angled lead portions 28 and may optionally extend inbetween individual die packages 10 towards the lateral casing sides 21.

The stacked system 100 may be formed by a method that includes stackingthe die packages 10 a-d and forming the connectors 114 at individualleads 16 of the die packages 10 a-d. Stacking and aligning the leads 16may include stacking the die packages 10 a-d in sequence so that theleads 16 of one package are placed above or below corresponding leads onan adjacent die package and so that the leads 16 of a lower packageproject upwards towards the leads 16 of an upper package. The connectors114 may be formed using wave or reflow soldering processes. In wavesoldering processes, a pumped wave or cascade of liquid-phase metalsolder can be applied across the angled lead portions 28. In reflowsoldering processes, solder paste having metal powder particles can beapplied across the angled lead portions 28 and then heated to melt themetal particles. In these or other soldering processes, the metal solderselectively wets (e.g., when heated) to at least a portion of theexterior lead surfaces 25 and optionally a portion of the interior leadsurfaces 26, but the solder does not wet to the dielectric material ofthe casing 14. The connectors 114 are formed and individual leads 16 ofan individual die package 10 are coupled with corresponding leads on anupper or lower die package when the metal solder cools. In otherembodiments, some of the individual leads 16 may not physically contacta corresponding lead on an immediately adjacent die package such thatonly certain leads are interconnected with the adjacent die packages. Inany these embodiments, the connectors 114 may bridge a vertical gapbetween vertically aligned leads 16 of adjacent dies (see, e.g., FIG. 9,reference 68). A vertical lead spacing distance of 60 microns or less,for example, may create adequate surface tension for forming a solderbridge between the individual leads 16.

In general, and in contrast to the stacked system 100, conventionalmethods of stacking packages or dies have been challenging andexpensive. For example, because conventional leads are not arranged toface a dielectric casing or project towards an above-located diepackage, they can be difficult to position and can collapse underneath apackage if not accurately aligned. In addition, attaching a conventionallead on one package to a conventional lead on a corresponding package istime-intensive and requires careful manual manipulation and inspectionof each conventional lead-to-lead interconnection. For example, theconventional leads on an above-located die package are generally bentdownward so that they project towards the lead on a below-located diepackage. When the conventional leads undergo an attachment process, thelead-to-lead connection needs to be inspected to verify that the bentlead is correctly positioned with the package below. Also, the processof stacking conventional packages is difficult to standardize becausedies are made in a variety of sizes, and packages likewise vary in size.Thus, the process of stacking and interconnecting conventional packagesneeds to be tailored to an arrangement of a particular package type.

Several embodiments of microelectronic die packages 10 can be easy tostack and are robust. For example, after stacking and aligning the diepackages 10 a-d, the leads 16 of corresponding die packages areautomatically sufficiently aligned for the connectors 114 to intercouplethe leads and do not require manual manipulation to align the individualleads with respect to one another. Further, because the leads 16 extendoutwardly from the lateral sides of the casing 14, they provide acontact surface that is located on both lateral and angled portions ofan individual lead; this enables the die packages 10 a-d to beintercoupled using a simple soldering process and creates reliablelead-to-lead interconnections that do not require stringent alignmenttolerances. Also, the lateral casing sides 21 of the die package 10 canprevent the leads 16 from collapsing during die package stacking byproviding a surface for an individual lead 16 to compress or spring backupon. In addition, the leads 16 can further establish the exteriorpackage dimensions such that a standardized package size may be used tohouse a variety of differently sized dies as explained in further detailbelow with reference to FIG. 10.

FIGS. 2A-8B illustrate stages of forming a microelectronic die packagein accordance with several embodiments of the disclosure. FIG. 2A is atop view of a microelectronic assembly 40 that includes a metal frame 41situated on top of a release layer 45. The frame 41 comprises leadportions 42, openings 43, and dicing lanes 44. The openings 43 expose aportion of the release layer 45 for attaching and positioning a die 12(FIG. 1) adjacent to the lead portions 42, and the dicing lanes 44provide a cutting or cleavage path for singulating an individual diepackage from the frame 41 (described further with reference to FIGS. 8Aand 8B). In one embodiment, the frame 41 may be made from copper and mayinclude selective copper plating along the lead portions 42. In otherembodiments, the frame 41 may comprise a variety of other metallicmaterials such as aluminum or an aluminum-copper alloy. The releaselayer 45 may be, for example, a thermal or UV release film.

FIGS. 2B and 2C are partially exploded cross-sectional side views of theassembly 40 showing the frame 41, the lead portions 42, the releaselayer 45, and a support substrate 47 (e.g., a silicon wafer or othertype of structure having planar surface). FIG. 2B further shows anindividual dicing lane 44, and FIG. 2C further shows gaps 48 between theindividual lead portions 42. The gaps 48, along with the openings 43 andthe support substrate 47, define bottom and lateral sides of a cavity,which will be subsequently filled with a dielectric material (describedfurther with reference to FIGS. 4A-C). The individual lead portions 42are spaced apart from each other by a spacing distance s₁, which shouldbe large enough to prevent the connectors 114 from laterally bridgingacross individual leads.

FIG. 3A is a top view of the assembly 40 after attaching microelectronicdies to the release layer 45. FIG. 3A, more specifically, shows theframe 41, the lead portions 42, and the openings 43 with individual dies12 placed within the openings 43 and adjacent to the lead portions 42.FIGS. 3B and 3C are cross-sectional side views further showing theopenings 43 and the lead portions 42, which are below a top-side surfaceof the dies 12 and have a thickness t₁. In several embodiments, the leadportions 42 may have a thickness t₁ in the range of about 50 to 250microns.

FIG. 4A is a top view of the assembly 40 after a dielectric material 50has been formed on a top side of the metal frame 41 and a top side ofthe dies 12. The dielectric material 50, for example, may be a polymeror plastic that is heated and subsequently deposited on top of andwithin the gaps of the frame 41. The dielectric material 50, forexample, can be molded over the frame 41 and the top sides of the dies12. FIGS. 4B and 4C are cross-sectional side views showing thedielectric material 50 filling the openings 43 around the dies 12 andthe gaps 48 between the lead portions 42. After curing or cooling, thehardened dielectric material 50 should form a protective andelectrically isolative covering over the dies 12, within gaps betweenlateral sides of the dies 12 and the lead portions 42, and within thegaps 48 between the lead portions 42. The dielectric material 50 mayoptionally extend above the dies 12 by a thickness t₂ to completelyencapsulate all of the dies 12 and lead portions 42.

FIGS. 5A and 5B are cross-sectional side and bottom views of theassembly 40 after removing the release layer 45 and the supportsubstrate 47 to expose bottom-side surfaces 52 (e.g., active side) ofthe dies 12 and expose bottom-side surfaces 54 of the lead portions 42.The bottom-side surfaces 52 of the dies 12 include bond pads 56 (oractive features) electrically coupled to an integrated circuit withinthe dies 12 (not shown). The dielectric material 50 holds the dies 12 inplace and separates the dies 12 from the lead portions 42.

FIG. 6 is a cross-sectional side view of the assembly 40 after formingan embodiment of the dielectric spacer layer 34 at the bottom-sidesurfaces 52 of the dies 12. The spacer layer 34 includes the metaltraces 32 electrically coupling the bond pads 56 to the lead portions 42and the package bond pads 36. The spacer layer 34 may be made from amaterial such as a non-conductive oxide or polymer. The metal traces 32and the package bond pads 36, for example, may be made from copper oraluminum. The spacer layer 34 can accordingly be a redistributionstructure. It is also expected that in certain embodiments, the packagebond pads 36 may be omitted. For example, in FIG. 1 the package bondpads of the die packages 10 b-d could be omitted because these pads arenot electrically connected to any external bond pads.

FIG. 7 is a cross-sectional side view of the assembly 40 after removinga portion of the dielectric material 50 by a chemical etch,backgrinding, or chemical-mechanical polishing process to form thecasings 14. The dielectric material 50, for example, can be etched toexpose the interior lead surfaces 26 (FIG. 1) and to form the top sides22 and lateral casing sides 21 of the casings 14. Additionally, althoughshown as having sloped surfaces, the lateral casing sides 21 may beformed in other embodiments so that they are generally perpendicular tothe top casing side 22. It is expected, however, that sloped, curved,tapered, or otherwise graded profiles of the lateral casing sides 21provide an individual lead with room to bend or compress underneath anabove-situated lead or die package. Also, sloped lateral casing sides 21may be used to increase a lateral spacing distance between an individuallead and an upper portion the lateral casing side 21 to provide moreroom for forming a connector on the interior lead surface 26.

FIG. 8A is a cross-sectional side view of an embodiment of the package10 a after singulation through the dicing lanes 44 (e.g., by trim andform equipment) to yield separated dies 12 housed in the casings 14 andcoupled to individual “L”-type leads 16. FIG. 8B shows an alternativeembodiment after singulation of a die package 60 a that is formed tohave individual “C”-type leads 66 that include a tiered lead portion 67laterally extending toward the lateral casing sides 21. In bothembodiments, the lateral lead portion 29 projects away from the lateralcasing side 21, the angled lead portion 28 extends away from the laterallead portion 29 so that the interior surface region 27 is generallyaligned with a surface at the lateral casing side 21, and the exteriorlead surface 25 generally faces away from the lateral casing side 21 andis arranged to receive an external inter-package connector. The angledlead portion 28 may include a variety of angled, curved, or otherwisesloped profiles, which can optionally include a profile that issubstantially perpendicular to the lateral lead portion 29 or a profilethat is substantially sloped toward the lateral casing side 21. In theembodiment of FIG. 8B, the angled lead portion 28 is substantiallyperpendicular with the lateral lead portion 29, and the angled leadportion 28 positions the tiered lead portion 67 above the lateral leadportion 29. This allows an individual lead 66 to accommodate additionaltypes of external inter-package connectors, such as metal solder bumps(see, e.g., FIG. 9). Accordingly, the die package(s) 10 a or 60 a may beplaced within a stacked system, such as the stacked system 100, and theconnectors 114 can be formed along the die packages 10 a or 60 a at anyof the exposed or otherwise accessible surfaces of the leads 16 or 66 atthe angled lead portion 28, the lateral lead portion 29, or the tieredlead portion 67.

FIG. 9 is a cross-sectional side view of an embodiment of a stackedsystem 200 that includes the individual die package 60 a as well as diepackages 60 b-d physically coupled together, at least in part, byadhesive layers 112 a-c. The leads 66 of the die packages 60 a-d arephysically and electrically coupled together by external inter-packageconnectors 214. In this embodiment, the connectors 214 include metalsolder bumps interposed between the tiered lead portions 67 and thelateral lead portions 29 on corresponding die packages. The leads 66 ofthe individual die packages 60 are vertically separated from each otherby a gap 68 spanning a distance t₃, which may be on the order of 60microns or less. Individual connectors 214 bridge the gaps 68 and attachto portions of the exterior lead surfaces 25 along the tiered leadportions 67 as well as the angled and lateral lead portions 28-29.Similar to the stacked system 100, the stacked system 200 may be formedby a method that includes stacking the die packages 60 a-d such that theleads 66 of the die packages 60 a-d are aligned, and forming theconnectors 214 at individual leads 66 of the die packages 60 a-d. Theconnectors 214 may be formed using a metal solder bump process thatincludes forming a dot of metal solder that attaches to portions of theexterior lead surfaces 25. As shown, the dot of solder may be configuredto attach to the exterior lead surface 25 along the angled lead portions28 such that the connectors 214 are positioned between the individualdie packages 60 a-d and project outward from the lateral lead portions29. In other embodiments, the connectors 214 may be further coupled toportions of the interior lead surfaces 26.

FIG. 10 is a cross-sectional side view showing an embodiment of astacked system 300 that includes microelectronic die packages 72 a-chaving corresponding microelectronic dies 74 a-c. The die packages 72a-c share a common lateral dimension d₁, but the microelectronic dies 74a-c have different lateral dimensions d₂, d₃, and d₄ (not in thatorder). In one embodiment, the stacked system 300 may be a memory modulethat includes an interface circuit at the die 74 a, a control circuit atthe die 74 b, and a memory at the die 74 c. Because the packages 72 a-cshare the common lateral dimension d₁, a myriad of different types ofstacked systems may be created by stacking preferred die packages orexchanging certain die packages. For example, an alternative embodimentof the DRAM-based memory module could be assembled by using smallermagnetoresistive RAM (MRAM) based dies housed in die packages having thelateral dimension d₁. Accordingly, DRAM-based die packages 72 b-c couldbe exchanged for MRAM-based die packages.

FIG. 11 is a cross-sectional side view showing an embodiment of astacked system 400 that includes microelectronic die packages 82 a-dseparated by dielectric spacer layers 84 a-d and having correspondingfirst metal leads 86 a-d and second metal leads 88 a-d respectivelycoupled together by first and second connectors 414 a-b. In this view,the spacer layer 84 a includes corresponding metal traces 90 a-b, thespacer layer 84 c includes corresponding metal traces 91 a-b, the spacerlayer 84 d includes a single metal trace 92, but the spacer layer 84 bdoes not have any corresponding metal traces along this view of thesecond package 82 b (i.e., the die packages 82 a-d may have a differentarrangement of metal traces in other cross-sectional views such that thesecond package 82 b does not have metal traces along the illustratedcross-section). The first connector 414 a is applied across the firstleads 86 a-d to selectively electrically couple first, third, and fourthpackages 82 a, 82 c, and 82 d; and the second connector 414 b is appliedacross the second leads 88 a-d to selectively electrically couple thefirst and third packages 82 a and 82 c. Thus, one side of the diepackage 82 d and both sides of the die package 82 b are electricallyisolated from the connectors 414 a-b. The process of stacking the diepackages 82 a-d can be the same as the process described with referenceto FIGS. 1 and 9. The process of forming the die packages 82 a-d can besimilar to the method of manufacturing described with reference to FIGS.2A-8B, but instead of connecting a metal trace to every metal lead,individual metal trace-lead couplings have been omitted.

Many other types of variations may be made to the above describedstacked systems, including various combinations of certain featuresassociated with these systems. For example, in lieu of the bond padconnections 106 (FIGS. 1 and 9), wire bonds may electrically couple astacked system to an interposer substrate. In some embodiments, theadhesive layers interposed between the stacked packages may be omitted.The external inter-package connectors alone, for example, could be usedto hold individual die packages together by temporarily clamping thepackages until metal solder is applied and the connectors are formed. Inother embodiments, the connectors can be configured to selectively routeindividual sets of the leads by applying metal solder across a limitednumber of leads. Leads that are not soldered remain electricallyisolated from the stacked system. In one specific embodiment, a stackedsystem includes die packages that house the same type of die. Forexample, a stacked system could be a memory, such as a static dynamicaccess memory (SRAM). In this embodiment, individual leads would provideword and bit line access to individual SRAM dies housed in theindividual die packages. Accordingly, the aggregated individual SRAMdies form a large SRAM, which has a reduced footprint relative to aconventional SRAM of the same size. Also, the stacked system may includeany number of individual microelectronic die packages having more orfewer packages than those presented in the illustrated embodiments.

Any one of the microelectronic devices described above with reference toFIGS. 1-11 can be incorporated into any of a myriad of larger or morecomplex systems 490, a representative one of which is shownschematically in FIG. 12. The system 490 can include a processor 491, amemory 492 (e.g., SRAM, DRAM, Flash, or other memory device),input/output devices 493, or other subsystems or components 494.Microelectronic devices may be included in any of the components shownin FIG. 12. The resulting system 490 can perform any of a wide varietyof computing, processing, storage, sensor, imaging, or other functions.Accordingly, representative systems 490 include, without limitation,computers or other data processors, for example, desktop computers,laptop computers, Internet appliances, hand-held devices (e.g., palm-topcomputers, wearable computers, cellular or mobile phones, personaldigital assistants), multi-processor systems, processor-based orprogrammable consumer electronics, network computers, and minicomputers.Other representative systems 490 include cameras, light or otherradiation sensors, servers and associated server subsystems, displaydevices, or memory devices. In such systems, individual dies can includeimager arrays, such as CMOS imagers. Components of the system 490 may behoused in a single unit or distributed over multiple, interconnectedunits, e.g., through a communications network. Components canaccordingly include local or remote memory storage devices and any of awide variety of computer-readable media.

From the foregoing, it will be appreciated that specific embodimentshave been described herein for purposes of illustration, but well-knownstructures and functions have not been shown or described in detail toavoid unnecessarily obscuring the description of the foregoingembodiments. Where the context permits, singular or plural terms mayalso include the plural or singular term, respectively. Moreover, unlessthe word “or” is expressly limited to mean only a single item exclusivefrom the other items in reference to a list of two or more items, thenthe use of “or” in such a list is to be interpreted as including (a) anysingle item in the list, (b) all of the items in the list, or (c) anycombination of the items in the list. Additionally, the term“comprising” is inclusive and is used throughout to mean including atleast the recited feature(s) such that any greater number of the samefeature or additional types of other features are not precluded. It willalso be appreciated that specific embodiments have been described hereinfor purposes of illustration, but that various modifications may be madewithout deviating from the inventions. For example, many of the elementsof one embodiment can be combined with other embodiments in addition to,or in lieu of, the elements of the other embodiments. Accordingly, theinvention is not limited except as by the appended claims.

1. A stacked system of microelectronic devices, comprising: a firstmicroelectronic device having a first bottom side and first metal leadscoupled to the first bottom side, wherein a first dielectric casingdefines at least a portion of the first bottom side; a secondmicroelectronic device having a top side, a lateral side, a secondbottom side, a second bottom side bond-site, and second metal leadscoupled to the second bottom side, the second leads including a lateralportion that laterally projects away from the lateral side, a tieredportion that laterally projects towards the lateral side, and an angledportion between the lateral portion and the tiered portion thatpositions the tiered portion above the lateral portion, wherein a seconddielectric casing defines at least a portion of the top side; anadhesive layer positioned between the top side of the secondmicroelectronic device and the bottom side of the first microelectronic;metal solder bumps between individual first leads and individual tieredportions of the second leads; a support substrate adjacent to and spacedapart from the second bottom side, the support substrate having asubstrate bond-site; and a substrate connector attached to the substratebond-site and to the second bottom side bond-site.
 2. The stacked systemof claim 1 wherein the metal solder bumps are further attached to theindividual second leads of the second microelectronic device at asurface of the angled portion that generally faces away from the lateralside of the second casing.
 3. The stacked system of claim 1 wherein thetiered portion is separated from a corresponding first lead by avertical distance of up to 60 microns.
 4. The stacked system of claim 1wherein the angled portion is substantially perpendicular to the lateralportion.
 5. The stacked system of claim 1 wherein the angled portion issubstantially perpendicular to the tiered portion.
 6. The stacked systemof claim 1 wherein the first dielectric casing has a first lateraldimension substantially equal to a second lateral dimension of thesecond dielectric casing.
 7. The stacked system of claim 1 wherein thesecond microelectronic device has a redistribution structure at thesecond bottom side.
 8. The stacked system of claim 7 wherein theredistribution structure includes layered metal traces.
 9. A stackedsystem of microelectronic devices, comprising: a first microelectronicdevice having a first die, a first bottom side, and first metal leadscoupled to the first bottom side, wherein the first die has a firstlateral dimension; a second microelectronic device having a second die,a top side, a lateral side, a second bottom side, a second bottom sidebond-site, and second metal leads coupled to the second bottom side, thesecond leads including a lateral portion that laterally projects awayfrom the lateral side, a tiered portion that laterally projects towardsthe lateral side, and an angled portion between the lateral portion andthe tiered portion that positions the tiered portion above the lateralportion, wherein the second die has a second lateral dimension; metalsolder bumps between individual first leads and individual tieredportions of the second leads; a support substrate adjacent to and spacedapart from the second bottom side, the support substrate having asubstrate bond-site; and a substrate connector attached to the substratebond-site and to the second bottom side bond-site.
 10. The stackedsystem of claim 9 wherein the first lateral dimension is different thanthe second lateral dimension.
 11. The stacked system of claim 9 whereina first dielectric casing defines at least a portion of the first bottomside, and wherein a second dielectric casing defines at least a portionof the top side, and wherein the first and second dielectric casingshave substantially equal lateral dimensions.
 12. The stacked system ofclaim 9 further comprising an adhesive layer positioned between the topside of the second microelectronic device and the bottom side of thefirst microelectronic.
 13. The stacked system of claim 9 wherein themetal solder bumps are further attached to the individual second leadsof the second microelectronic device at a surface of the angled portionthat generally faces away from the lateral side of the second casing.14. The stacked system of claim 9 wherein the tiered portion isseparated from a corresponding first lead by a vertical distance of upto 60 microns.
 15. The stacked system of claim 9 wherein the angledportion is substantially perpendicular to the lateral portion.
 16. Thestacked system of claim 9 wherein the angled portion is substantiallyperpendicular to the tiered portion.
 17. The stacked system of claim 9wherein the second microelectronic device has a redistribution structureat the second bottom side.
 18. The stacked system of claim 9 wherein theredistribution structure includes layered metal traces.
 19. A stackedsystem of microelectronic devices, comprising: a first microelectronicdevice having a first die, a first bottom side, and first metal leadscoupled to the first bottom side, wherein the first die has a firstlateral dimension; a second microelectronic device having a second die,a top side, a lateral side, a second bottom side, a second bottom sidebond-site, and second metal leads coupled to the second bottom side, thesecond leads including a lateral portion that laterally projects awayfrom the lateral side, a tiered portion that laterally projects towardsthe lateral side, and an angled portion between the lateral portion andthe tiered portion that positions the tiered portion above the lateralportion, wherein the second die has a second lateral dimension differentthan the second lateral dimension; metal solder bumps between individualfirst leads and individual tiered portions of the second leads; asupport substrate adjacent to and spaced apart from the second bottomside, the support substrate having a substrate bond-site; and asubstrate connector attached to the substrate bond-site and to thesecond bottom side bond-site.
 20. The stacked system of claim 19 whereina first dielectric casing defines at least a portion of the first bottomside, and wherein a second dielectric casing defines at least a portionof the top side, and wherein the first and second dielectric casingshave substantially equal lateral dimensions.